Question and answer services generally allow users to post questions, or to access questions or answers that were previously posted by other users. Typically, any user of a question and answer service can leave a comment or an answer in response to a question. A user can respond to a question with a bona fide answer, a comment, another question, an emoticon, symbols, nonsensical information, spam, or with any other response. While some answers are useful to the user that posed the question, others may not be.